Chain stitch device for a sewing machine



I United States Patent [1113,536,021

[72] Inventor Tofu Kuromegawa 687,511 ll/1901 Amrnerman 112/168 OsakaJapan 859,423 7/1907 Ammerman.. 112/ 168 N0. 1118,6235) 1968 863,489 8/ 1907 Ammerman... 1 12/168 v. 3,181,490 5 1965 4s Patented Oct. 21,1970 Kawasaki 1 12/252 Assignee Mama sewing Machine Co. Lat Primary Exammer-Alfred R. Guest Osaka, Japan Attorneys-Frank H. Marks and Nathan N. Kraus [32] Priority Nov. 30, 1967 [33] Japan [31] 42/ 77,104 ABSTRACT: A device for converting a conventional lockstitch sewing machine to produce a chainstitch. The [54] cw STITCH DEVICE FOR A SEWING device comprises a body having a generally cylindrical portion MACHINE adapted for attachment to the bobbin arbor of the machine for 5 CI 26 D Fi rotation with the shuttle. The cylindrical portion has a tapered [52] us CL 8 u2/l68 $250k arid Itgread-rgiii iding and thrleadgtfiking means adjacent nec a exte mg transverse y o e axis of the cylind i Int. Cl. D05b l/l4 cal portion. The thread-guiding means is so shaped that, in a Field Search 1 first rotational cycle of the shuttle, it will draw a thread loop I l 22 Z5Z(CUISOTY) hooked by the shuttle beak on to the neck. The thread-taking means, in a second rotational cycle, is adapted to lead the loop [56] References C'ted to the external side of the threaduidin means while the UNITED STATES PA N g g 514653 2/1894 H b 1 TE TS Ishuttle beak lS picking up a thread for the next succeeding e er mg 112/168 00p.

Patented Oct. 27, 1910 v 3,536,021

INVENTOR TORU KUROMEGAWA BY Q TORNEY:

Patented Oct. 27, 1970 Sheet 3 of 5 Patented Oct. 27, 1976 Sheet 5 01 5 CHAIN STITCH DEVICE FOR A SEWING MACHINE This invention relates to chainstitch sewing apparatus fitted in the shuttle in lieu of the bobbin case of an ordinary lockstitch sewing machine equipped with a semicircularly moving rotary shuttle, permitting one to make chainstitches, utilizing the upper thread.

One object of my invention is to provide means for forming chainstitches by the use of a lockstitch sewing machine equipped with a conventional semicircularly rotating shuttle.

Another object of my invention is to provide means for producing chainstitches making use of the conventional semicircularly rotating shuttle by replacing the bobbin case in said shuttle with the chainstitch apparatus of my invention.

Still another object of my invention is to provide means for obtaining satisfactory chainstitches with apparatus of simple structure consisting of a thread-guiding member and a body member.

A further object of my invention is to provide novel chainstitch apparatus readily mountable in and removable from a shuttle.

The above and other objects and advantages of my invention will be described in detail hereunder, according to preferred embodiments shown in the accompanying drawings, wherein FIG. I is an end elevational view of a shuttle fitted with one embodiment of my invention;

FIG. 2 is a fragmentary side elevational view, partly in longitudinal axial section, of the foregoing;

FIG. 3 is a plan view of the thread guide of my invention;

FIGS. 4 to 16 are plan views illustrating the functioning of the device at various stages;

FIG. 17 is a transverse or axial view showing the relation between the apparatus of the invention and the shuttle;

FIG. 18 I, II, III, IV, are diagrams indicating the relations between the apparatus of the invention and the thread loop;

FIG. 19 is a plan view of another embodiment of the inventron;

FIG. 20 is an elevational view, partly in fragmentary longitudinal section, of the foregoing;

FIG. 21 is a plan view illustrating the operation of the foregoing;

FIG. 22 is a plan view of still another embodiment of the invention;

FIG. 23 is an axial view similar to FIGS. 2 and 20 of the foregoing embodiment;

FIG. 24 is a diagram illustrating the operation of the foregoing embodiment;

FIG. 25 is an elevation of another embodiment of the invention, and

FIG. 26 is a plan view of the foregoing.

In FIGS. 1 and 2, numeral 1 represents a sernicircularly rotating shuttle movable in shuttle face 21 of a conventional lockstitch sewing machine, and having a radially extending beak 2 and an arbor 3 on which to journal the bobbin thread case, not shown. Numeral 4 represents a cylindrical body portion of one embodiment of the invention having a thread guide arm fixed at the front end thereof. Tapered neck portion 6 of body 4 at the rear of thread guide 5 is tapered from neck 6 toward the middle part of the body 4, providing a tapered face At the front end of body 4 is an axial bore 7 in which the front end of arbor 3 is joumaled. Inside body 4 is loosely fitted an oscillating ring 8, a projection 9 at the upper end thereof being loosely fitted into a slot on the upper side of body 4. An operating finger piece formed at the lower end thereof fits loosely in an oblong aperture at the lower part of body 4, a coil spring 11 urging the oscillating ring 8 backward, being also fitted axially within body 4. A pin 13 projecting from the end of body 4 is disposed in an aperture 12 provided on the bottom face of shuttle for the purpose of locking the body 4 to the shuttle in a particular relationship.

Body 4 may be mounted on arbor 3 by applying pressure to body 4, after fitting oscillating ring 8 inside said body 4 and assembling same to the arbor 3, as shown in FIG. 2. Oscillating ring 8, being urged forward by arbor 3, allows said arbor freely to pass through, the front end of arbor 3 being fitted into bore 7, consequently, the rear end of body 4 is brought into close contact with the bottom face of shuttle l.

The fitting process is then completed so that pin 13 is seated within aperture 12. In this arrangement oscillating ring 8 is obliquely engaged with arbor 3, as seen in FIG. 2, preventing body 4 from being dislocated from arbor 3. When oscillating ring 8 is revolved forwardly, with projection 9 as a center, by operating finger 10, oscillating ring 8 and arbor 3 fit loosely so that body 4 may easily be removed from the shuttle 1. Thread guide arm 5 is formed with a thread taker b inclined toward shuttle 1, said thread taker being located on the side of the loop taker or beak 2 of the shuttle.

The forming of chainstitches by the apparatus of this invention just described, is as follows:

Referring to FIGS. 4-8, the upper thread 15 of the needle 16, which has ascended, after first penetrating cloth I4 and then the needle hole 19 of needle plate 17, is hooked by beak 2 of shuttle I, which has commenced its regular clockwise rotation, said thread 15 forming a loop L encircling the outside of shuttle l which rotates as indicated in FIGS. 5 and 6 and is caught on neck 6. As shuttle 1 rotates as from FIG. 6 to FIG. 7, the upper thread 15 is gradually pulled up, loop L escaping the shuttle l at the position where its regular rotation is completed, as seen in FIG. 7. Then, as cloth 14 starts to move and shuttle I commences its reverse rotation, the upper thread 15 is pulled farther up, both sides of loop L caught on neck 6 of body 4 being brought in contact with the front face of shuttle I in a state of tension, as seen in FIGS. 8 and 9. At this point, cloth 14 remaining stationary, needle 16 descends through cloth 14 into loop L, said needle I6 descending further into loop L when the rotation of shuttle 1 reaches the final point of its reverse rotation, as indicated in FIG. 10.

When the shuttle starts its regular rotation and beak 2 thereof hooks up the upper thread 15 by the reverse face on both sides of loop L, as seen in FIG. 11, thread taker b of thread guide 5 enters loop L and said thread guide 5 proceeds still deeper into loop L as shuttle I continues its rotation, the right side of the loop L preceeding to the front of thread guide 5 At this point beak 2 draws the upper thread 15, preparing the next loop L which is the pass through loop L, as indicated by FIG. 12. As the shuttle rotates further, loop L comes off thread guide 5, as seen in FIG. I3 and loop L commences to hang on body 4 by reason of the elevation of the upper thread As shuttle l rotates further (FIG. 14), the loop L is contracted as the cloth 14 commences to move (FIG. 15). Loop L becomes taut when shuttle 1 starts to make a reverse rotation (FIG. 16), a loop stitch 23 being formed as a result.

Such stitches are made in sequence by a repetition of the foregoing operational cycle.

The chainstitch apparatus, needle 16 and shuttle l are so arranged that needle 16 will pass inside the loop already formed (FIG. 10) i. e., inside the triangle formed by the lines connecting the external periphery of neck 6 and needle hole 19 of nee dle plate 17.

As to the limits of the height of neck 6 of body 4, the lowest point is at the position where the thread coming off beak 2 of shuttle I is caught on neck 6v The rear end 22 of shuttle I, when said shuttle 1 makes a reverse rotation, can rotate without hooking up either loop L or loop L which is caught on neck 6, as indicated in FIGS. 8 and 16.

The upper limit may be set on the production of a line connecting needle hole 19 and the highest point of thread tightener 22 of shuttle 1.

In view of the fact that the tapering face a of body 4 performs the function of guiding loop L to neck 6 as loop L of upper thread 15, caught on the external side of shuttle 1 is transferred to body 4 (FIGS. 6-7), it is desirable that taper ing face a be so arranged that loop L will be brought in contact with tapering face a when said loop L is taken up by body 4. By this arrangement, as shuttle 1 makes a reverse rotation, as

from the position of FIG. 7 to that of FIG. 8, loop L reaches neck 6, guided by thread tightener 22 of the shuttle.

The dimension of tapered face a is so determined that the loop wound onto body 4 from the shuttle may be constantly located on said tapered face a, whereas said face is formed in such a shape as will guide the loop to neck 6 in coordination with thread tightener 22.

The position of thread guide 5 is so determined that thread taker b of said thread guide is located in the space e inside loop L caught on neck 6 in the situation wherein shuttle 1 has completed its reverse rotation, said thread guide 5 being fixed to shuttle 1 at the foregoing position by pin 13 and hole 12 (FIG. 20).

As illustrated in FIG. 11, thread taker b takes up the righthand thread of the loop caught on neck 6, the radial position of said thread taker b being determined by the height of neck 6 and thread tightener 22. The lower the position of thread taker b, the easier it is for the said thread taker to enter loop L. However, if said height is too small, the thread taker pulls the right-hand thread of the loop toward the left when shuttle 1 makes a reverse rotation (FIG. 18, IV), with the result that the thread taker is prevented from being located inside loop L.

As to the highest limit, it is appropriate to determine the position of the thread taker so that it may be located at the back of the loop of upper thread 15 formed by neck 6 and needle hole 19 (FIG. 17). If thread taker b is located on the right side of loop L in the state wherein shuttle I has completed its reverse rotation (FIG. 18, II), no stitch can be made, the thread taker being unable to take up the thread. If thread taker b were located on the left side of the loop L, having passed it over, the thread taker would take up the thread on both sides of loop L' at the same time, with the result that the thread, being unable to come through, would be broken off.

The radial position of thread taker b can be so determined that said thread taker is located between neck 6 and thread tightener 20.

The back c of thread guide 5 should be finished smooth so that the right-hand thread of the loop is not likely to be picked up as shuttle 1 makes a reverse rotation.

The appropriate height and shape of thread guide 5 will be so determined that, as the thread is wound up on body 4 coming off the beak 2, said thread cannot escape the front face of the thread guide 5 without coming on contact therewith. For this purpose, the greater part of thread guide 5 protrudes further than the front face of shuttle 1, as indicated in FIG. 2. Though thread taker b recedes from the front face of shuttle 1 (FIG. 2), it is not always necessary that the thread taker be located further inward than the front face of shuttle l, as is apparent from the position of the thread taker as seen in FIG. 17.

In the embodiment of FIGS. 19 and 20, the internal hole 24 of body 4 throughout the whole length thereof has a diameter fitting arbor 3 of shuttle 1. On one side of body 4 is formed a slit 25 into which is inserted a spring 26, the external end thereof being pulled outside of body 4 and fastened with a screw 27. The internal end of said spring 26 is bent to form a hook 28 engaging a groove 29 on the external periphery of the front end of arbor 3 in the state wherein the rear end of body 4 is in contact with the bottom surface of shuttle 1 and hole 12 and pin 13 are interengaged. The body is thus readily removable and also may be economically produced.

Thread guide 5' includes an arcuate flange 3 extending outwardly from arcuate slope f connecting thread taker b and the middle part of said thread guide.

In this embodiment, even when the sewing machine is operated at high speed, the external rim h of flange g guides the front side of loop formed with the upper thread hooked by beak 2 of shuttle 1 up to the reverse side of thread guide 5' with accuracy (FIG. 21), with the result that there is no risk of escape of the front side of the loop from the front side of thread guide 5' or of its being pulled up without being caught on body 4.

In the embodiment illustrated in FIGS. 22 and 23, the fitting of body 4 to arbor 3 is the same as in the case of the last described embodiment, the only difference being in the shape of thread guide 5" and the fact that a thread escape guiding member 30 is provided between thread guide 5" and shuttle bearing 21. bore In this embodiment, the central part of thread guide 5" is approximately circular, having no outwardly protruding part on the opposite side of thread taker b unlike the previously described embodiments. Instead, in this instance, there is provided a thread escape guiding member 30 consisting of a thick wire bent at approximately a right angle, at both ends thereof, one end of said wire constituting a shaft 31 which is revolvably fitted into a bore provided in body 4, the bent end portion 32 at the other end of the said wire being engaged in a notch 33 of shuttle bearing 21, leaving an appropriate space for thread escape. Thus, member 30 may not revolve when thread guide 5" revolves together with shuttle l.

Incidentally, the engaging notch of the arrester provided on the conventional bobbin may serve in lieu of said notch 33.

In this embodiment thread taker b of thread guide 5 guides the loop caught on neck 6" to the external side of said thread guide, separating the ascending loop from said thread guide while the loop on the external side of the thread guide is in the course of being lifted.

As per the foregoing description, the loop coming off body 4" and being lifted is in such a free state that, when the thread guide is revolving at high speed, said loop is likely to be broken off, having been caught on the thread guide or stuck between the next loop and body 4, resulting in imperfect tightening of the thread. However, when a thread escape guiding member, such as element 30 is provided, as in this embodiment, the loop is accurately controlled by said member 30 m the course of the thread escape and this hazard is prevented In the embodiment illustrated in FIGS. 25 and 26, body 4 is provided with a guide fin 34 on the external periphery thereof the other features being substantially as in the embodiment of FIGS. 19 and 20.

The object of fin 34 in this embodiment is partly to support the loop wound up by body 4 from shuttle l, preventing the loop from moving downward and also to guide said loop to neck 6 by way of the tapering face a, preventing the loop from being caught on the rear part of body 4. Consequently, the axial position of said fin 34 must be so determined that the loop wound on body 4 may be located between fin 34 and thread guide 5. A tapering face a is formed between fin 34 and neck 6, as illustrated in FIG. 26, so that the loop located between fin 34 and thread guide 5 may be guided to neck 6, in accordance with the rotation of body 4, by the operation of thread tightener 20 and tapering face a.

This invention, as described above, permits production of chainstitches by simply fitting my improved apparatus on the bobbin thread case arbor of the conventional semirotary shuttle, and thus the conventional sewing machine may be used without modification. Both lockstitch and chainstitch can be made simply by interchanging the apparatus of this invention with the conventional bobbin thread case, or vice versa. Moreover, the apparatus of this invention can be conveniently fitted to the shuttle simply by fitting the body of my said apparatus upon the shuttle arbor without the need of screws or the like.

Various changes coming within the spirit of my invention may suggest themselves to those skilled in the art; hence. I do not wish to be limited to the specific embodiments shown and described or uses mentioned, but intend the same to be merely exemplary, the scope of my invention being limited only by the appended claims.

I claim:

1. In combination in a sewing machine having a work sup port formed with a needle aperture, a thread-carrying eyepointed needle supported above the work support for endwise reciprocation through said needle aperture, a semirotary reciprocable shuttle having a loop forming beak and a bobbin arbor fixed in the cavity of said shuttle, a chainstitch device comprising:

a. a general cylindrical body having a bore to receive said arbor to effect attachment of said body to said arbor for rotation therewith;

b. said body having a tapered neck portion;

c. a generally flat arm adjacent said neck portion and extending laterally of the axis of said body;

d. said arm having thread guiding and thread taking means;

e. said thread guiding means being shaped to draw a thread loop hooked by said beak in a first rotational cycle onto said neck portion; and

f. said thread taking means including a hook portion inclined towards said shuttle and being disposed in close proximity to said beak and in a second rotational cycle being adapted to lead said loop to the external side of said thread guiding means while said beak is picking up the thread to form a next succeeding loop.

2. The invention as defined in claim 1 including a guide fin on the periphery of said cylindrical body.

3. The invention as defined in claim 1 including means for removeably securing said body on said arbor.

4. The invention as defined in claim 1 including an annular groove in said arbor and a detent carried by said body and engageable in said groove to releasably secure said body on said arbor.

5. The invention as defined in claim 1 including a rodlike thread escape member extending radially of said arbor and having a laterally bent terminal portion at each end, one of said temrinal portions being received in a central bore in said body and the other of said terminal portions extending into a recess in the race of said shuttle. 

